I first start by commenting out the lines in /etc/httpd/conf.d/welcome.conf to disable the default page. It’s good to have it in the beginning to know you have Apache working, but after that it can safely be disabled.
Make sure the <b>DirectoryIndex</b> directive includes ‘index.html’ or whatever.whatever you wish to load by default when one is not specified:
DirectoryIndex index.html index.html.var
You say index.htm in one sentence, but index.html in another. If it’s index.htm, then it won’t load by default until you add it to the DirectoryIndex.
Do the following and copy the output to your next reply if you’re still having problems:
cat /etc/httpd/conf/httpd.conf |grep -v ^# |grep -v ^$
Look at /var/log/httpd/error.log for more information. At the command line, you can do ‘tail -f /var/log/httpd/error.log’ and then open the URL and look at the output as it happens to see what errors are being generated.